Okay, unfortunately I am more and more confused by your posts.
If the Silverstone chassis has a full motherboard in it, it’s not a dumb disk array, it’s a whole separate computer that needs it’s own CPU, RAM and OS to be functional. At that point just install TrueNAS on that system and be done with it.
If the Silverstone box is the one with the ASUS MB I know exactly nothing about your other box that you want to connect to the Silverstone one.
Please start over.
Clearly and thoroughly describe the hardware you have, if there’s even more than one system and all the components in each chassis.
Also explain what your end goal with the system(s) is.
Maybe I will come back tomorrow and look at this again. Maybe.